System for cleaning components for filling holes in a printed circuit board with a fluid fill material

ABSTRACT

A method for cleaning components of a system for filling holes in a printed circuit board with a fluid fill material includes removing the components being a dispensing head and a manifold connected to the dispensing head preferably as a single unit. The single unit is retained in that format. Excess fluid material from the dispensing head and manifold is evacuated preferably by passing air through the dispensing head and manifold. Then the dispensing head and manifold is placed in a cleaning tub, and the manifold is attached to a solvent pump line. The dispensing head and manifold is flushed with a flow of solvent from the solvent pump line; and excess solvent from the dispensing head and manifold is evacuated, by passing air through the dispensing head and manifold.

BACKGROUND

The present disclosure relates to placing fill materials into the holesof a substrate, such as placing an electrically conductive, thermallyconductive or nonconductive paste into holes within printed circuitboards (PCB), wired circuit boards, hybrid circuit boards, ceramicsubstrates, and other various laminate and electronic packages andpanels.

Vias, holes, or openings are common structures found in PCBs and otherelectronic panels. The intent is to uniformly fill the plurality of viasor holes on a substrate with a desired fill material.

However, a common issue with the current application systems is theundesirable levels of fill variation, including the lack of fillmaterial in some holes and excessive fill material in others, resultingin substantial material waste. Especially with squeegee print fillingsystems and processes, fill material flow is often non-uniformlyrestricted in random holes.

In other application systems, an air pressure action is used to forcepaste from a paste tube through a dispenser. The dispenser moves acrossa substrate or panel while dispensing the paste into holes within thepanel. These application systems may yield potential defects caused bythe preparation of the materials or by the application method itself.With these application systems, it is difficult to reliably place pastein a hole without forming an air pocket or void. This is partially dueto variations in the substrate (thickness, hole diameter to be filled,density of holes in any given area across the panel). Fluctuations inthe air pressure pushing the fill material also result in erratic ratesof paste flow through the dispenser. Another problem is that the pasteor fill material within a tube may be introducing variations inviscosity and flow, resulting in uneven application, inadequate and/orexcessive fill. For example, the viscosity of the paste in the center ofthe tube appears to be different than the viscosity of the paste in thebeginning of the tube. There is also a concern that the use of airpressure may penetrate, blow-by, or compromise the seal in the pastetube and create air voids in the paste supply.

These issues combine to produce poor quality fill (voiding) within thevia or hole and result in an excessive amount of fill material waste andexpense while attempting to adequately fill the substrate holes. Therecan also be excess paste under a leading edge of the dispenser thattypically cannot be reused. The excess paste is usually cured anddiscarded, as there is a potential for paste contamination caused byO-ring debris, catch pans, etc. The excessive material waste creates aneed to constantly add more paste to the application systems toreplenish the paste volume in the dispenser.

It is important that the vias or holes must be completely filled withpaste so that there are no air pockets. If there are voids or airpockets in the paste, these air pockets generally remain in thecompleted product. A via with a void has several adverse effects. If thepaste is placed to provide thermal conductivity, the air of the voidacts as an insulator. If the paste is placed to provide electricalconductivity, an opening at the void results in no secondary or failsafe electrical connection being formed. Furthermore, if the via isfilled to provide structural integrity, a void in the via results inreduced structural integrity.

Thus there is a need for an improvement to the current hole fillapplication systems. There is a need for a process and apparatus foruniformly placing fill material with minimal waste into the holes of anelectronic substrate such that there are no air pockets formed in theplugged fill material. The process and apparatus needs to be able toform plugged holes in a substrate which have reliable electricalconductivity, thermal characteristics, and/or structural integrity.There is a need for a process and apparatus that improves the yield forforming plugged holes in electronic substrates while lessening thepossibility that contaminates will be introduced into the fill material.Furthermore, there is a need for a hole fill process which iscontrollable and which has a high throughput, such as in a relativelyhigh speed, single pass operation. There is also a need for a effectiveand time efficient cleaning process and apparatus to clean the hole fillapparatus with minimal disassembly.

SUMMARY

In accordance with one aspect of the present disclosure, a hole fillsystem is provided. The disclosed system is provided for enhancing theflow of fill material from a pump assembly through a manifold to adispensing head to fill the holes of a substrate.

In accordance with another aspect of the present disclosure, a system isprovided for improving the cleaning process of the manifold anddispensing head assembly.

In one exemplary embodiment, the disclosed system is obtained byreplacing and improving various components of a base system produced byMASS GmbH (Germany) and identified as the Vacuum Chamber Plugging, VCP5000-1™.

DESCRIPTION OF THE DRAWINGS

The above-mentioned features and objects of the present disclosure willbecome more apparent with reference to the following description takenin conjunction with the accompanying drawings wherein like referencenumerals denote like elements and in which:

FIG. 1 is a schematic perspective view of a hole fill system fordelivering fill material to fill the holes on a substrate.

FIG. 2 is a second view of the hole fill system of FIG. 1.

FIG. 3A is a view of components of the hole fill system, including afeeding reservoir, outlet system, manifold, and dispensing head.

FIG. 3B is a view of the dispensing head and the manifold of the holefill system of FIG. 2.

FIG. 4 is a view of the dispensing head and manifold of the hole fillsystem of FIG. 2, the dispensing head and manifold having been removedas a single unit and placed within a basin to be connected to an airsupply.

FIG. 5 is a view of the dispensing head and manifold in the hole fillsystem of FIG. 2, the dispensing head and manifold having been removedas a single unit and placed within a cleaning box. The manifold inlet isconnected to an inlet port inside a cleaning box that is connected to asolvent container.

FIG. 6 is a view of a second embodiment of a manifold and the channelsprovided by the manifold.

FIG. 7 is view of the second embodiment of the manifold of FIG. 6 andthe channels provided by the manifold connected to a dispensing head.

FIG. 8 is a view of the dispensing head and manifold of the hole fillsystem of FIG. 7, the dispensing head and manifold having been removedas a single unit and placed within a cleaning box. The manifold inlet isconnected to an inlet port inside a cleaning box that is connected to asolvent container.

DETAILED DESCRIPTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings which form a part hereof,and in which are shown by way of illustration specific embodiments inwhich the disclosure may be practiced. It is to be understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from the scope of the present disclosure.

Devices and methods are disclosed for delivering a fill material, suchas electrically/thermally conductive paste, and/orelectrically/thermally insulating paste, and/or solder paste to asubstrate such as an electronics package, PCB or any other electronicplanar surface.

There is a system for filling holes in a substrate with a fluid fillmaterial. The system comprises a main body for receiving, preferablyvertically, a printed circuit board within the main body. By having thesystem clamp vertically instead of horizontally, there is a saving ofspace. The system does not require a pre-routed backer panel. O-ringsare used on both sides, namely the fill head and receiving head, toprovide an adequate seal. Paste or fill material viscosity is not reliedupon to provide an adequate seal, which also results in less tooling,setup, and cleaning time.

A feeding reservoir contains the fill material and has a first end and asecond end. In an exemplary implementation, the feeding reservoir is acylindrical tube of fluid fill material.

An outlet system connects the first end of the feeding reservoir to thedispensing head and allows the fill material to flow from the first endof the feeding reservoir to the dispensing head. The outlet systemincludes a flow path having a flow line attached to a manifold assemblyleading to the dispensing head. The inner diameter of the flow line issized to accommodate a desired flow of fill material. In one embodiment,the flow line has an inner diameter of ⅜ inch.

The manifold assembly or branch network includes branches that do nothave 90° elbows in the flow path. This allows for smoother flow of thefill material and easier cleaning of the manifold assembly compared toflow paths that have 90° elbows. The number of branches and junctionsmay be varied as desired, depending on various factors such as the sizeof the dispensing head, the viscosity of the fill material, and thedesired flow rate of the fill material in the dispensing head.

In one embodiment, the manifold includes a single channel splitting at ajunction into two secondary channels, the two secondary channels eachsplitting again into two tertiary channels. The total of four tertiarychannels are connected at their respective opposite ends to thedispensing head. In one embodiment, there are no 90° elbows and O-ringsprior to the junctions where the single channel splits and where thesecondary channels split. In other embodiments, in addition to nothaving 90° elbows and O-rings prior to the junctions, there are also no90° elbows and O-rings where the tertiary channels are connected to thedispensing head.

In one exemplary implementation, the channels of the manifold compriseof hollow tubes. The hollow tubes may be made of rubber, plastic, or anyother material that is preferably inert to the fill material that passesthrough the tube. In another exemplary implementation, the channels arecreated within a block or multiple blocks of material, such as aluminum,steel, plastic, or any other material that is preferably inert to thefill material. In one embodiment, a center aluminum block joins togethertwo side aluminum blocks to form a “Y”-shaped manifold. Smooth channelswith no 90° elbows are formed within the aluminum blocks manifold. Thediameter of the channels are sized to accommodate a desired flow of fillmaterial. In one embodiment, the channels have diameters of ⅜ inch. Thechannels are also preferably highly polished to provide enhance flow ofthe fill material. A single channel splits into two secondary channelswithin the center aluminum block, each secondary channel connecting to arespective side aluminum block. The secondary channel splits into twotertiary channels within each side aluminum block. The total of fourtertiary channels are connected to the dispensing head. In otherexemplary implementations, a combination of tubes and channeled blocksis used to form the manifold.

A plunger is located at the second end of the feeding reservoir. An aircylinder driven system acts as a pressure source to push the plungerinto the feeding reservoir, thereby forcing the fill material out of thefirst end of the feeding reservoir and into the dispensing head. The aircylinder driven system provides a steady and consistent pressure forcingthe fill material from the feeding reservoir, through the outlet system,and out of the dispensing head. In one exemplary implementation, a SMC™air cylinder is used. Specific software may be used with the hole-fillsystem to control the pressure generated by the air cylinder.

The pressure source may include one or more hydraulic, pneumatic ormechanically driven pressurizing cylinders, and may include a ram pressfor back-filling paste vessels. Back-filling is desirable to prevent airentrapment during the paste loading process. The paste flow is alsocontrolled with a vacuum pressure release valve. In some embodiments, acontrolled output ultrasonic driver is attached to the dispensing head.An output control mechanism is used with the ultrasonic driver.

A dispensing head is coupled to the source of pressurized fill materialby a fill material inlet. The dispensing head includes a main body orpressure chamber and a gasket or wear element positioned along thesurface of the dispensing head. The dispensing head dispenses the fillmaterial that flows into the main body from a plurality of inlets. Theplurality of fill material inlets share a common orientation and aredirected away from the outlet system. In an exemplary implementation,the dispensing head also includes a flow dispersion regulator whichincludes a punctured feed tube positioned within the main body, thepunctured feed tube having a plurality of flow regulating openings. Theflow regulating openings in the punctured feed tube are sized tomaintain a substantially constant pressure at each of the flowregulating openings.

Positioned on the surface of the main body of the dispensing head is aflow equalization grid. The flow equalization grid includes amultiplicity of openings or fill material outlets. In an exemplaryimplementation, the dispensing head comprises a plurality of elongatedoutlets and the dispensing mechanism disperses fill material along thelength of each outlet of the plurality of outlets.

There is also a method for cleaning the components of a system forfilling holes in a substrate with a fill material. A dispensing head anda manifold connected to the dispensing head is removed preferably as asingle unit. The single unit is retained in that format. Excess fluidmaterial from the dispensing head and manifold is evacuated preferablyby passing air through the dispensing head and manifold. The single unitcomprising the dispensing head and manifold is placed in a cleaning tub,and the manifold is attached to a solvent pump line. The dispensing headand manifold is flushed with a flow of solvent from the solvent pumpline. Excess solvent from the dispensing head and manifold is evacuatedby passing air through the dispensing head and manifold.

Overview

FIG. 1 is a schematic perspective view of a hole fill system 100 fordelivering fill material 110 to fill the holes 132 on a substrate 130.The system 100 includes a main body for receiving a vertically placedsubstrate 130 within the main body. There is a dispensing head 200 forselectively dispensing the fluid fill material 110 onto the verticallyplaced substrate 130, the dispensing head 200 having a plurality ofholes 500, as shown in FIG. 3B. The hole fill system 100 of the firstembodiment includes a mechanism 150 for moving the dispensing head 200.The system also comprises a head parking mechanism and a substratesupport structure 180.

As shown in FIG. 2, the dispensing head 200 is placed in contact withand moved along substrate 130 by movement mechanism 150 while fillmaterial is forced through dispensing head 200 and into the holes 132contained in substrate 130. Substrate support structure 180 supports thesubstrate 130 and head parking mechanism helps prevent loss of fillmaterial between passes of dispensing head 200 along substrate 130.

As shown in FIG. 3A, a feeding reservoir 400 contains fill material 110and has a first end and a second free end 127. The feeding reservoir 400is preferred to comprise a pressure chamber such as pressure chamber orpaste tube 141 attached to the transverse support member 158. Pressureat which the feeding reservoir provides fill material may be referred tohereinafter as the fill material pressure.

The feeding reservoir 400 of the hole fill system 100 includes abackplated ram press chamber which comprises a paste tube 141 havingtherein a plunger or cylinder 410. The plunger 410 is located towardsthe second end of the feeding reservoir. The action of the cylinder orplunger 410 is under the force of an air cylinder 411 which ismechanically linked to the plunger 410 through rod 412. There is acollapsible sock 413 about the rod 412 to keep the mechanism sealedagainst inadvertent ingress of impurities into the system. The aircylinder 411 pushes the plunger 410 into the feeding reservoir 400,thereby forcing the fill material 110 out of the free end 127 of thefeeding reservoir 400 and into the dispensing head 200.

The control for pressure can be two way. During a print stroke or whenpaste is provided to the dispensing head 200, pressure is applied to theplunger. When the print stroke is complete, the dispensing head 200moves to a staging or parked area. The flow of pressurized fill material110 can be reversed by placing a slight vacuum on the plunger 410 sothat the fill material within the paste tube, the outlet system, as wellas the dispensing head 200 retracts slightly. This prevents waste offill material 110.

In other variations, some of the embodiments may be combined in anembodiment which utilizes a stepping motor in addition to or as asupplement to the air pressure cylinder system 411 to move a plunger410. The stepping motor can move the plunger 410 to force fill material110 out of chamber 400 and through flow line 120.

Although fill material 110 may comprise any material which can be usedto pressure fill the holes of a substrate, it is contemplated that theuse of electrically conductive or nonconductive and/or thermallyconductive or nonconductive pastes may be particularly advantageous,particularly in instances where the substrate comprises an electronicspackage member.

An outlet system of channels and couplings connect the end 127 of thefeeding reservoir to the dispensing head 200. The outlet systemcomprises a flow line 120 connected to the first end 127 of the feedingreservoir. In one embodiment, free end 127 from the chamber 141 isconnected to the flow line 120 without there being any right angularelbows or O-rings in the line. The single tube provides smooth laminarflow for the fill material from the first end of the feeding reservoirto a manifold assembly.

The outlet system comprises a flow line 120 and in one exemplaryimplementation, as shown in FIGS. 3A and 3B, a manifold of secondarybranch tubes 121 and 122 and tertiary branch tubes 123, 124, 125, and126. The manifold includes a T-piece 128 which splits the outlet fromflow line 120 into the two secondary branches 121 and 122. This is noright angular elbow in front of the T-piece 128. There are also no rightangular elbows in lines 121 and 122, and the downstream ends of thoselines 121 and 122 connect respectively with T-pieces 129 and 131. Thereare no right angular elbows in front of the T-pieces 129 and 131 andsecondary branches 121 and 122 split into tertiary branches 123, 124,125, and 126. The lateral free ends of tertiary branches 123 to 126connect directly with the inlets of dispensing head 200 without anyright angular elbows.

In another embodiment, there is a 90 degree elbow connecting flow line120 to outlet 127 to facilitate equipment clearance. FIG. 6 and FIG. 7show an alternative embodiment of a manifold comprised of blocks ofmaterial having smooth channels with no 90° elbows created within. Acenter block 610 joins together two side blocks 620, 640 to form a“Y”-shaped manifold 600. A single channel 602 splits into two secondarychannels 604, 605 within the center block 610 and each secondary channelis connected to a side block 620, 640. The secondary channel splits intotwo tertiary channels within each side block. The four tertiary channels606, 607, 608, and 609 are connected to the dispensing head 200.

As shown in FIGS. 3A and 3B, the dispensing head 200 includes a mainbody portion 210 and an O-ring or gasket 220 that surrounds a flow grid500. There can also be a flow dispersion regulator passing through mainbody 210.

The main body 210 and the gasket 220 may be made from any suitablematerials, but are preferably made from materials that will remain inertwith respect to the fill material/via fill paste that will pass throughthe dispensing head 200. Examples of such materials include, but are notnecessarily limited to, machine-anodized aluminum, stainless steel,solvent-resistant polymer, and Teflon-impregnated Delrin. In lesspreferred embodiments, main body 210 and/or gasket 220 may comprise acomposite of materials and/or pieces.

It is contemplated that the gasket 220 should be made of a material thathas suitable wear characteristics, yet will seal when a fairly low forceis applied by the dispensing head to the surface of the electronicspackage. The gasket is preferably machined from Teflon or cast in a moldwith 40 to 120+ durometer hardness polymer, or silicon rubber. Thegasket can be resurfaced and configured in various lengths and shapes toaccommodate different sized print areas for injecting fill material tovarious configurations of holes in electronic packages or substrates.

There is a mechanism for moving the dispensing head 200 that includes atransverse support member 158, rails, coupling members, and a guidedhead support mechanism. The mechanism also includes pneumatic moversattached to sides of a guided head support. The pneumatic movers areused to control the movement of the dispensing head 200 with respect tothe support member 158, and are also used to control the amount of forceor pressure between the dispensing head 200 and the plate 130. Specificsoftware may be used with the hole-fill system to control the speed ofthe dispensing head moving along the substrate.

There are screw threaded bars 150 which operate through threadedapertures 151 to guide the dispensing head upwardly and downwardly inthe mechanism 100 and provide support to the head support 158. Thesupport member 158 is threadingly movable along the threaded rods 150which inter-engage in the apertures 151.

In alternative embodiments the dispensing head 200 can be attached toany common screen-printing machine via a transverse bar on the printerswhich replaces support member 158.

The head 200 must be mounted to the movement mechanism in such a way asto provide uniform planarity with the substrate or surface to beprocessed. Bearing blocks and rails by providing support to guided headsupport help prevent “wobbling” of guided head support as it is moved upand down by movers.

Operation

A substrate 130 is positioned with a support structure 180, and the holefill system is slid up against substrate 130. When thus positioned, thesystem protects any tooling holes near the edge of substrate 130 whichare not to be filled, and provides a mechanism by which the dispensinghead 200 may be moved onto and from the substrate 130 with minimal lossof fill material 110.

Once the substrate is positioned, the dispensing head is positioned sothat the gasket 220 is in sealing contact with substrate 130 andsurrounds one or more holes 132. Positioning the gasket in contact withsubstrate 130 is accomplished via pneumatic movers which maintain aspecific force between the gasket 220 and the substrate 130, and bymovement of support member 158 along rails or rods 150.

Pressure is then applied to the source of fill material so as to causethe fill material to flow through channels and connectors, throughdispensing head 200, out of grid openings 500, as shown in FIG. 3B andFIG. 7, and into holes 132. More specifically, the pressure mechanism411 produces a pressure within the flow line 120 which is attached tothe multiple channels forming a manifold linkage to the dispensing head200. The pressurized fill material flows through the channels andconnectors into the dispensing head 200. In some embodiments, the fillmaterial flows through a flow dispersion regulator in the main body ofthe dispensing head. The pressure is equalized by orifices or openingswithin the flow dispersion regulator in the main body. After enteringthe dispensing head, the fill material then flows through aflow-equalizing grid with openings 500. From openings 500, the fillmaterial flows against the surface of substrate 130 that is sealedagainst head 200, and into holes 132.

As the holes 132 are filled, the dispensing head is moved to anotherlocation on the substrate 130 where there are additional holes. Suchmovement is accomplished as engagement between dispensing head 200 andsubstrate 130 and flow of pressurized fill material 110 is maintained,and the support member is moved along the rails to cause the dispensinghead 200 to move down the panel 130. As the head 200 remains inengagement with substrate 130, a more or less continuous amount ofpressurized fill material 110 flows from the pressure source through thechannels and connectors and into the dispensing head 200 for injectioninto the holes 132 within the substrate 130.

While the dispensing head 200 is positioned operatively, the substrate130 that has its desired holes filled is removed from the supportstructure and another substrate is placed on the support structure. Theprocess for filling the holes then repeats.

The fluid pressure of the fill material 110 and vacuum release can becontrolled either manually or by tying it to a stop-activated switch setto specific substrate print length. In another embodiment, a machinevision system can be substituted for the stop-activated switches. Themachine vision system would produce a signal when the selected holepattern area has been filled.

In alternative embodiments, dispensing head 200 may be positioned sothat fill material 110 is forced into holes 132 of substrate 130. Thepanels or electronics packages 130 are pulled over an dispensing head200 and then exit on the opposing side where the panel or electronicpackage is removed and a fresh panel is loaded for hole filling in acontinuous fashion. This second embodiment will have a high throughputsince plates or electronics packages can be continuously fed and filledusing this system. The dispensing head 200 does not move as much as inthe first embodiment. In the second embodiment, the dispensing head 200moves up and down or into and out of engagement with the substrate 130.The substrates are moved over the dispensing head 200 as the holes arefilled.

The dispensing head moves by activating a pneumatic, two-sided pressurecylinder having adjustable travel of approximately 1 to 3 inches to meetthe panel surfaces or electronic package 130 surfaces to be filled. Thetwo sided pressure cylinder is attached to a guided head supporting baras is dispensing head 200. Scavenger blades can be positioned on eitherside of the substrate 130.

Advantageously, the hole fill system of the present disclosure ispreferably an apparatus which employs a method for placing fill materialinto holes in electronic packages so that there are reduced numbers ofair pockets formed in the fill material. The hold fill system decreasesthe amount of processing time required per board, provides for the useof a wider variety of fill materials, and minimizes wastage andcontamination of fill material. In addition, if air pockets are formed,the air pockets have less volume than the air pockets or voids formedusing other methods. As a result, the apparatus and related processresult in plugged holes which are reliable electrical contacts and havefavorable thermal characteristics, and the process has improved yieldsfor electronic packages which use plugged holes.

The manufacturing process is controllable and has a relatively highthroughput during manufacturing. Such high throughput is obtained bydecreasing the amount of process time required per board.

The device can lessen the chances that contaminates will be introducedinto the fill material. The reduced chance of introduction ofcontaminates is contemplated as resulting from providing a sealed flowpath for the fill material from the fill material source to the holesbeing filled.

Furthermore, the device and process can also be used to place fillmaterial in holes having high aspect ratios and small diameter withadded control for filling the holes. Fillable holes 132 can havediameters in the range of 2/1000ths of an inch to 25/1000ths of an inchin diameter. Preferably the diameters are less than 12/1000ths of aninch. More preferably the diameters are less than 8/1000ths of an inch,and most preferably the diameters are less than 6/1000ths of an inch. Inaddition, the aspect ratio associated with these holes, i.e. the ratioof the hole depth divided by the hole diameter, that can be filled arefrom 1:1 to 17:1, depending on material rheology, paste solids loading,and particle size distribution within the fill material used. Preferablythe aspect ration is greater than 5:1. More preferably the aspect ratiois greater than 10:1, and most preferably the aspect ration is greaterthan 12:1.

The pump assembly provides a significant level of improvement relatingto hole fill consistency and quality within the filled holes.Furthermore, it has also shown a large reduction in fill material waste.For example, using Taiyo paste on an 11.2:1 aspect ratio design,conventional hole fill systems only yielded 3 panels from each tube ofpaste. The disclosed arrangement yields 13 panels from each tube ofpaste. This is an improved paste utilization by 4.333 times. This is asubstantial savings in material costs. Furthermore, the resulting pasteapplication on the panel may no longer require a scavenging operation toremove excess paste. This provides labor and productivity savings.

Advantageously, the hole fill system utilizes a lower fill materialpressure to fill holes. It should be noted that substrate 130 can be ofany type. For example, plates or electronics packages containing holesmay be used even if such plates or packages comprise laminates orceramics. In addition, holes in wired circuit boards may also be filledusing one or more of the embodiments discussed herein.

Panels that have dot plating, namely button plating patterns can befilled using the disclosed system, which was previously not possiblesince the copper dots would chew up the Teflon faceplate and excessiveamounts of paste would exit. The disclosed hole fill system (includingthe air cylinder, manifold, etc.) results in 80% less paste waste thanin prior art systems.

Cleaning Operation

The method for cleaning components of a system for filling holes 132 ina substrate 130 with a fill material 110 comprises the steps of removingthe components being a dispensing head 200 and a manifold of channelsand connectors connected to the dispensing head 200. As shown in FIG. 4,excess fill material is first evacuated from the dispensing head andmanifold by passing air from an air supply 500 through the dispensinghead 200 and manifold of connectors and tubes. At this stage thedispenser and manifold can be in a basin 501.

As shown in FIG. 5 and FIG. 8, the dispensing head 200 and manifold arethen placed in a cleaning tub 502. A solvent pump line 505 connected toa solvent supply 504 is attached to the manifold. The dispensing head200 and the manifold system is flushed with a flow of solvent from thesolvent pump line 505. In one exemplary implementation, the outlet forthe solvent line 505 is connected to a nipple provided in a wall in thetub 502 so that a circuit is made with solvent supply 504.

Excess solvent is evacuated from the dispensing head 200 and manifold bypassing air through the dispensing head 200 and manifold system as shownin FIG. 4.

The components being the dispensing head 200 and a manifold systemconnected to the dispensing head can be removed from the hole fillsystem 100 as a single unit.

The manifold system includes channels and connectors to the dispensinghead. The manifold system includes a flow path having the single flowline attached to a branch manifold network leading to the dispensinghead. In one embodiment, the single flow line branches into twosecondary channels, and each secondary channel branches in turn to twotertiary channels. The tertiary channels are attached to the dispensinghead without 90° elbows in the flow path. This allows for more thoroughand efficient cleaning of the manifold system.

In one exemplary implementation, the manifold system for cleaning caninclude a single tube splitting at a junction into two tubes, the twotubes being connected at their respective opposite ends to thedispensing head. In another exemplary implementation, the manifoldsystem for cleaning can include a block or multiple blocks of materialwith channels created within. In other cases, the manifold system to becleaned can have a different manifold of tubes, channels, andconnectors. The manifold can have different formats and shapes ofconnectors.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reviewing the abovedescription. The scope of the disclosure should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

The invention claimed is:
 1. A method for cleaning components of asystem for filling holes in a printed circuit board with a fluid fillmaterial, the method comprising the steps of: removing the componentsbeing a dispensing head and a manifold connected to the dispensing head,the removal being to separate the components from the filling system;coupling a supply line for air to the manifold and placing thedispensing head and manifold in a first container; firstly evacuatingexcess fill material from the dispensing head and manifold by passingair through the dispensing head and manifold while in the firstcontainer; placing the dispensing head and manifold in a cleaning tub,the cleaning tub being different to the first container; attaching themanifold to a solvent pump line through a nipple attached to thecleaning tub; secondly flushing the dispensing head and manifold with aflow of solvent from the solvent pump line; removing the manifold anddispensing head from the cleaning tub; re-coupling the supply line forair to the manifold and re-locating the dispensing head and manifold inthe first container; and thirdly evacuating excess solvent from thedispensing head and manifold by passing air through the dispensing headand manifold.
 2. The method as claimed in claim 1 wherein the manifoldincludes a single channel splitting at a junction into two channels, thetwo channels being connected at their respective opposite ends to thedispensing head.
 3. The method as claimed in claim 2 wherein aconnection with the dispensing head is at a location towards therespective ends of the dispensing head.
 4. The method as claimed inclaim 1 wherein the manifold is connected to the solvent pump line andincludes channels and connectors to the dispensing head, the channelsand connectors having different branches, and wherein the channelsinclude a first channel, branching to two secondary channels, andwherein each secondary channel branches in turn to two tertiarychannels, and wherein the four tertiary channels are attached to thedispensing head, and wherein at least some of the junctions betweenadjacent channels are formed in a non-right-angular relationship withadjacent channels.
 5. The method as claimed in claim 4 wherein themanifold comprises a center block and a plurality of side blocks havingchannels within, the center block being connected to the solvent pumpline, and wherein a first channel branches to two secondary channelswithin the center block, each secondary channel being connected to aside block and branching in turn to two tertiary channels within theside block, the four tertiary channels being connected to the dispensinghead, and wherein at least some of the junctions between adjacentchannels are formed in the absence of a right-angular relationship withadjacent channels.
 6. The method as claimed in claim 1 wherein an outletsystem includes a flow path having the solvent pump line attached to amanifold leading to the dispensing head, the manifold includingconnectors between the channels and with the absence of 90° elbows inthe flow path.
 7. A method for cleaning components of a system forfilling holes in a printed circuit board with a fluid fill material, themethod comprising the steps of: removing the components being adispensing head and a manifold connected to the dispensing head as asingle unit, the removal being to separate the components from thefilling system; coupling a supply line for air to the manifold andplacing the dispensing head and manifold; firstly evacuating excess fillmaterial from the dispensing head and manifold by passing air throughthe dispensing head and manifold; placing the dispensing head andmanifold in a cleaning tub; attaching the manifold to a solvent pumpline through a nipple attached to the cleaning tub; secondly flushingthe dispensing head and manifold with a flow of solvent from the solventpump line; removing the manifold and dispensing head from the cleaningtub; re-coupling the supply line for air to the manifold; and thirdlyevacuating excess solvent from the dispensing head and manifold bypassing air through the dispensing head and manifold.
 8. The method asclaimed in claim 7 wherein the manifold includes a single tube splittingat a junction into two tubes, the two tubes being connected at theirrespective opposite ends to the dispensing head.
 9. The method asclaimed in claim 8 wherein a connection with the dispensing head is at alocation towards the respective ends of the dispensing head.
 10. Themethod as claimed in claim 7 wherein the manifold is connected to thesolvent pump line and includes channels and connectors to the dispensinghead, the channels and connectors having different branches, and whereinthe channels include a first channel, branching to two secondarychannels, and wherein each secondary channel branches in turn to twotertiary channels, and wherein the four tertiary channels are attachedto the dispensing head, and wherein at least some of the junctionsbetween adjacent channels are formed in a non-right-angular relationshipwith adjacent channels.
 11. The method as claimed in claim 10 whereinthe manifold comprises a center block and a plurality of side blockshaving channels within, the center block being connected to the solventpump line, and wherein a first channel branches to two secondarychannels within the center block, each secondary channel being connectedto a side block and branching in turn to two tertiary channels withinthe side block, the four tertiary channels being connected to thedispensing head, and wherein at least some of the junctions betweenadjacent channels are formed in the absence of a right-angularrelationship with adjacent channels.
 12. The method as claimed in claim7 wherein an outlet system includes a flow path having the solvent pumpline attached to a manifold leading to the dispensing head, the manifoldincluding connectors between the channels and with the absence of 90°elbows in the flow path.
 13. A method for cleaning components of asystem for filling holes in a printed circuit board with a fluid fillmaterial, the method comprising the steps of: removing the componentsbeing a dispensing head and a manifold connected to the dispensing headas a single unit; the removal being to separate the components from thefilling system; coupling a supply line for air to the manifold andplacing the dispensing head and manifold in a first container; firstlyevacuating excess fill material from the dispensing head and manifold bypassing air through the dispensing head and manifold while in the firstcontainer; placing the dispensing head and manifold in a cleaning tub;attaching the manifold to a solvent pump line through a nipple attachedto the cleaning tub; secondly flushing the dispensing head and manifoldwith a flow of solvent from the solvent pump line; removing the manifoldand dispensing head from the cleaning tub; re-coupling the supply linefor air to the manifold and re-locating the dispensing head and manifoldin the first container; and thirdly evacuating excess solvent from thedispensing head and manifold.
 14. The method as claimed in claim 13wherein the manifold includes a single tube splitting at a junction intotwo tubes, the two tubes being connected at their respective oppositeends to the dispensing head.
 15. The method as claimed in claim 14wherein a connection with the dispensing head is at a location towardsthe respective ends of the dispensing head.
 16. The method as claimed inclaim 3 wherein the manifold is connected to the solvent pump line andincludes channels and connectors to the dispensing head, the channelsand connectors having different branches, and wherein the channelsinclude a first channel, branching to two secondary channels, andwherein each secondary channel branches in turn to two tertiarychannels, and wherein the four tertiary channels are attached to thedispensing head, and wherein at least some of the junctions betweenadjacent channels are formed in a non-right-angular relationship withadjacent channels.
 17. The method as claimed in claim 16 wherein themanifold comprises a center block and a plurality of side blocks havingchannels within, the center block being connected to the solvent pumpline, and wherein a first channel branches to two secondary channelswithin the center block, each secondary channel being connected to aside block and branching in turn to two tertiary channels within theside block, the four tertiary channels being connected to the dispensinghead, and wherein at least some of the junctions between adjacentchannels are formed in the absence of a right-angular relationship withadjacent channels.
 18. The method as claimed in claim 13 wherein anoutlet system includes a flow path having the solvent pump line attachedto a manifold leading to the dispensing head, the manifold includingconnectors between the channels and with the absence of 90° elbows inthe flow path.